A variety of factors have been shown to influence position timing and the content of positions taken by legislators on important issues. In addition to these observed factors, I argue that unobserved factors such as behind-the-scenes lobbying and party loyalty may also influence position timing and position content. Although hypotheses about observed factors can be tested using traditional methods, hypotheses about unobserved factors cannot. To test for systematic effects of unobserved factors on position timing and content, I develop a seemingly unrelated discrete-choice duration estimator and apply it to data from the vote for the North American Free Trade Agreement. The results indicate that even after controlling for observed factors, there is still evidence that unobserved factors such as Presidential lobbying and/or party loyalty influence both choices.

Author's note: I thank Doug Dion and Chuck Shipan for helpful comments and discussion. Previous versions of this paper were presented at the University of Iowa's Political Science Faculty Workshop and the University of California at Santa Barbara's Political Science Seminar Series. Financial support from the Robert Wood Johnson Foundation is gratefully acknowledged. Any errors or lapses in judgment are solely the author's responsibility. Replication materials are available on the Political Analysis Web site.

Footnotes

Author's note: I thank Doug Dion and Chuck Shipan for helpful comments and discussion. Previous versions of this paper were presented at the University of Iowa's Political Science Faculty Workshop and the University of California at Santa Barbara's Political Science Seminar Series. Financial support from the Robert Wood Johnson Foundation is gratefully acknowledged. Any errors or lapses in judgment are solely the author's responsibility. Replication materials are available on the Political Analysis Web site.

Box-Steffensmeier, Janet M., Arnold, Laura W., and Zorn, Christopher J. W.1997. The strategic timing of position taking in Congress: A study of the North American Free Trade Agreement. American Political Science Review91: 324–38.

Box-Steffensmeier, Janet M., and Jones, Bradford D.2004. Event history modeling: A guide for social sciences. Cambridge: Cambridge University Press.

Caldeira, Gregory A., and Zorn, Christopher. 2004. Strategic timing, position-taking, and impeachment in the House of Representative. Political Research Quarterly57: 517–28.

Fearon, James D.1994. Domestic political audiences and the escalation of international disputes. American Political Science Review88: 577–92.

Gomez, Brad T.2000. The dynamics of information exchange: Reevaluating the strategic timing of position taking in Congress. Paper presented at the 2000 annual meeting of the Midwest Political Science Association.

Lai, Brian, and Boehmke, Frederick J.2004. Empirically modeling strategic behavior with a unified model of crisis outcome and duration. Paper presented at the 2004 annual meeting of the American Political Science Association.

Lohmann, Susanne. 1993. A signaling model of informative and manipulative political action. American Political Science Review87: 319–33.

Lohmann, Susanne. 1994a. The dynamics of informational cascades: The Monday demonstrations in Leipzig, East Germany, 1989-91. World Politics47(1): 42–101.

Mathews, Donald R., and Stimson, James A.1975. Yeas and nays: Normal decision making in the U.S. House of Representatives. New York: Wiley.

Palazollo, Daniel J., and Swinford, Bill. 1994. Remember in November: Ross Perot, presidential power, and the NAFTA. Paper presented at the 1994 annual meeting of the American Political Science Association.

Wink, Kenneth A., Don Livingston, C., and Garand, James C.1996. Dispositions, constituencies, and cross-pressures: Modeling roll-call voting on the North American Free Trade Agreement in the U.S. House. Political Research Quarterly49: 749–70.

Wright, John R.1990. Contributions, lobbying, and committee voting in the U.S. House of Representatives. American Political Science Review84: 417–38.